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In its broader aspect this invention pertains to agricultural building heaters, that is, heaters, frequently called agricultural heaters, designed for use in farm buildings which house poultry, swine, livestock, and, in some instances, grains. More specifically the invention relates to gas fired circulating heaters having burner-fan assemblies widely used, among other buildings, in poultry or brooder houses.
Since the most important use of the heaters provided herein will be their installations in poultry houses where chickens and turkeys are grown, that aspect of the invention will be emphasized herein. The aim in poultry growing is to provide conditions that enable chicks to expend energy to increase body weight. Such a goal desirably results in larger, more saleable birds which resist disease. Temperature variations, however, cause chicks to expend energy to sustain their body temperatures rather than to increase their body weights. Such poultry house temperature variations thus lead to smaller, less desirable chickens and turkeys. Temperature variations can also create conditions during which weaker chicks contract diseases that can spread to healthier chicks. Obviously poultry farmers desire to maximize productivity by producing as much meat as possible for the feed consumed. Maintaining proper temperatures, then, is very important in effective poultry growing. It is desirable to keep poultry warm so that the food energy provided produces a gain in weight rather than body heat. To this end, for years the poultry industry has recognized the importance of allowing growing birds to choose their most comfortable areas. In order to provide such microclimates to precisely control them at the growing level, the poultry industry has relied on gas fired heating systems that typically include a plurality of gas burner assemblies in poultry houses. By strategically locating those heating assemblies throughout a poultry house, it is possible to provide an environment which is conducive to the growth of the birds in the flock.
There are two types of heating assemblies currently provided for poultry houses, radiant heaters, and forced air or fan heaters. However only radiant heaters appear to have found their way into the patent art. These radiant gas burner assemblies resemble outdoor yard gas lights, except that they are adapted to be suspended by chains and the like above the flock rather than being mounted on posts like the light fixtures. The most popular radiant heaters are the radiant screen type burners, a few examples being found in such patents as U.S. Pat. Nos. 5,964,214, 5,950,615, 5,328,357, and 4,614,166.
Radiant heaters are not completely satisfactory because they warm the growing birds but not the air. They heat only the side of the body that is within the reflective zone of the heater""s parabolic reflector. Humans can rotate their bodies to obtain some measure of comfort using the heat emanating directly from such heaters. But it is unlikely that chickens and turkeys will flip over to balance their heat intake. In addition since a radiant heater""s heat and light intensity are directly proportional to the gas input, it is impossible to maintain total darkness when the heaters are in operation. These disadvantages have led to the use of forced air heaters in poultry houses. Since a forced air heater is essentially a very hot flame with a fan behind it pushing large amounts of cold air passed the hot flame there is little room for improvement in such apparatus. This may account for our failure to find them in the patent art. The prior art, then is in the form of brochures published by the companies producing the heaters now on the market, such as the Airstream and Cumberland divisions of GSI of Assumption, Ill., Shenandoah Manufacturing Co., Inc. of Harrisonburg, Va., and Hired-Hand of Bremen, Ala. These heaters have numerous air inlets to admit those large amounts of air. Another popular gas fired heater, the L B White heater, sold by such companies as Gas Works in Yalesville, Conn., and Fort Recovery Equipment Co on line, is also provided with multiple air inlet ports. Fan heaters are generally mounted, not near the ceiling, but a few feet above poultry house floors in order to blow the heat generated by the burner close to the growing birds.
It is difficult to keep the ground warm when heavier colder air settles on it naturally. This has led poultry growers to attempt to lower, even more, their heaters, say to within inches of the floor to supply sufficient air to warm the dirt floors, especially when baby chicks are first introduced into a poultry house. The lowering of the heaters prevents the bedding area from becoming too cold, but it introduces other problems. As will become apparent, agricultural forced air heaters currently marketed for use in poultry houses are not totally satisfactory when used close to the floor.
A problem which is somewhat unique to the poultry industry is that dry feed, feathers and excrement which accumulate on dry poultry house dirt floors produce a remarkably dusty environment. To their disadvantage agricultural forced air heaters on the market are quite susceptible to the accumulation of such dust and other particles. Because of the accumulation of debris the heaters being marketed cannot be used very close to the poultry house floors. Whether the air born contaminants are kicked up by the young birds or emanate from the birds themselves, they can be ingested by the heaters. Contaminated air drawn into commercially available heaters results in accumulations which are detrimental to the burner, the fan motor, and other parts of the heater. Debris settles on horizontal surfaces within the heater, as well as on various other heater surfaces. Since these surfaces must be cleaned, the resulting maintenance of such systems adds significantly to the overall costs of raising the young chickens or turkeys. If the maintenance is deficient debris can gradually diminish the burner flame. The debris also settles on the motor and blower wheel within the heater causing the motor to run at temperatures above its design temperature. Given this environment it can be appreciated that prior art heaters are subject to improvement. It is these improvements which are within the contemplation of this invention.
As will be explained in greater detail hereinafter in conjunction with FIGS. 1 and 2 of the drawings, in order to admit incoming air the for their blowers and burners the commercial heaters have multiple openings for incoming air in the form of grid-like air intake ports on various heater sides. Other forced air agricultural heaters on the market are provided with similar grids for incoming air, but they are spaced across the heater floor. In the environment described the extensive use of air intake holes is quite disadvantageous. The incorporation of inlet air openings such as those shown in FIGS. 1 and 2 in the drawings leads to the debris problems alluded to. The inclusion of numerous air inlet openings does provide for greater air flow, and does produce the amount of heat desired. However it is to be realized that the intake holes require compensating adjustments. For instance, the large number of holes render it more difficult to ignite the burner within the time period set by the sensor. A higher gas pressure is required to initiate ignition. Low gas pressures lead to unreliable or failed ignitions due to lean mixtures. After ignition a high gas pressure is also required to compensate for the high air volume that flows through the burner. Since the air-to-fuel mixture required to sustain combustion subjects the heater surfaces to higher temperatures, the outsides of the heaters are hotter to the touch. A higher gas pressure requirement can also be a drawback because some actual field conditions may not be adapted to provide such a high gas pressure demands.
Due to the amount of wet litter and natural perspiration associated with such animals as chickens, turkeys, and pigs, the air within these animal confinements frequently becomes humid. Under these humid conditions it is virtually impossible to prevent the accumulation of debris on the motor and on the blower wheel, as well as around inlet openings and air passageways. Over time the heater""s internal air paths become restricted by accumulation, forcing the airstreams to make sharp turns. When this occurs there is a tendency for larger and heavier particles to fall out of the airstream as its velocity drops during changes in direction. If not removed, the deposits build up and become hardened by exposure to damp air. Eventually accumulations tend to form around the inlet openings and on critical surfaces. The buildup often decreases the air volume by obstructing the air passageways. The decrease in air volume, as previously noted, then causes the motor to overheat and run more slowly. In addition, since the heater""s gas valve generally is not designed for variable operation, the reduced inflowing air yields a richer fuel which produces a longer, larger, flame which burns hotter and more erratically. This resulting flame increases the combustion chamber temperature, and often activates the heater""s high limit switch or harms the inner working parts of the heater. As the debris continues to accumulate the motor will run less and less efficiently. By this invention forced air heaters for poultry houses are improved so that they do not permit accumulations such as those described. The result is that the heater, in effect, is self-cleaning. In addition the flame is not allowed to enter the blower wheel. The improvement herein also permits the poultry house heater herein to be suspended closer to the dirt floor than existing heaters.
Considering now one additional aspect, the eating habits of poultry are highly influenced by daylight hours. To take advantage of this, modern poultry growing techniques embody the practice by growers of simulating the passing of days by periodically darkening their poultry houses to create night-like conditions. The practice has been found to simulate different days. Undertaking this several times a day deceives the birds so that they eat more. This light control practice helps the birds grow faster. As an example, a free-range chicken usually requires up to ten months to attain a five and one-half pound dressed size. When light control techniques are employed chickens reach their five and one half pound dressed size in forty-two to forty-five days rather than the normal ten months. The net affect is that a grower can bring forth eight or nine flocks a year, thus greatly increasing the return on his investment.
Given the foregoing details relative to poultry house heaters it can be seen that militating against the light control practice is the fact that under certain less-than-optimum operating conditions, the higher gas pressure in prior art agricultural heaters causes a portion of the flame to be drawn into the blower wheel. The elongated portion of the flame entering the blower housing results in visible light which is then emitted through the heater""s exhaust opening, precluding total room darkness. In addition, the prior art heaters in FIGS. 1 and 2 do not offer double-wall combustion chamber protection in the case of light and heat since they utilize one or more of the exterior housing panels as part of the combustion chamber. Total darkness is further compromised because combustion light is emitted through the multiple air intake openings that are incorporated in prior art exterior housing panels. The gas fired agricultural heater provided herein does not emit any light at its sides or bottom, thus allowing for total nocturnal or simulated nocturnal darkness conditions in the poultry house. Further, by the improvement herein the poultry house heater, unlike those in the art, does not permit conditions which cause richer fuel flames.
A widely used type of agricultural heater is improved by this invention. The type of heater improved is a gas fired, forced air or fan heater having combustion, air mixing, blower and blower motor components assembled in a box-like or parallelepiped housing. The improvement herein includes interior heater compartment-forming panels which in combination with roof and floor panels form four distinct chambers within the housing. One of these chambers is a center blower chamber provided with a hot air outlet. On one side of the blower chamber, with a common wall between them, is an adjacent incoming cool air-heated air mixing chamber. On the other side, also separated by a common wall, is an adjacent motor chamber, such that the three chambers are in series. The fourth chamber is a combustion chamber whose location depends upon whether the chamber houses a vertical burner, or horizontal burner, which is new to this art. A blower is supported in the center blower chamber with its axis perpendicular to the common walls. A blower motor is mounted in the motor chamber on the common wall between the motor chamber and the blower chamber with its drive shaft extending into the blower chamber to be coupled to the blower. Air inlets open into the motor chamber, and as the only air inlets in the housing, those air inlets provide all of the air for the heater. Incoming air then initially cools the blower motor. Air passageways are provided to allow air to be drawn from the motor chamber into the air mixing chamber when the blower is operating. An opening in the common wall between the air mixing chamber and the blower chamber allows mixed ambient temperature air and hot air to flow into the blower. Openings leading from the motor chamber to the combustion chamber also allow incoming air to be drawn into the combustion chamber when the blower is operating. A passageway leading from the combustion chamber to the mixing chamber directs hot air from the combustion chamber into the mixing chamber to be mixed with incoming, ambient temperature air, to produce additional heated air to be drawn into the blower. The airflow within the heater thus is unidirectional, flowing, when the blower is operating, from the motor chamber into both the mixing chamber and the combustion chamber, and then into the blower chamber.